const fp = require("lodash/fp");
// 数据
// horsepower 马力， dollar_value 价格， in_stock 库存

const cars = [
  { name: "Ferrari FF", horsepower: 660, dollar_value: 700000, in_stock: true },
  { name: "Spyker C12 Zagato", horsepower: 650, dollar_value: 648000, in_stock: false },
  { name: "Jaguar XKR-S", horsepower: 550, dollar_value: 132000, in_stock: false },
  { name: "Audi R8", horsepower: 525, dollar_value: 114200, in_stock: false },
  { name: "Aston Martin One-77", horsepower: 750, dollar_value: 1850000, in_stock: true },
  { name: "Pagani Huayra", horsepower: 700, dollar_value: 1300000, in_stock: false },
];

// 练习1： 用fp.flowRight() 重写
// let isLastInStock = function(cars) {
//     // 获取最后一条数据
//     let last_car = fp.last(cars);
//     // 获取最后一条数据的in_stock属性值
//     return fp.prop('in_stock', last_car);
// }
const getProp = (key) => (data) => fp.prop(key, data);

const getStock = getProp("in_stock");
const isLastInStock = fp.flowRight(getStock, fp.last);
console.log('练习1: ', isLastInStock(cars));


// 练习2: 使用fp.flowRight()、fp.prop()和fp.first()获取第一个car的name
const geFirstCartName = fp.flowRight(getProp("name"), fp.first);
console.log('练习2: ', geFirstCartName(cars));


// 练习3: 使用帮助函数_average重构averageDollarValue, 使用函数组合的方式实现
let _average = function (xs) {
  return fp.reduce(fp.add, 0, xs) / xs.length;
};
// let _averageDollarValue = function (cars) {
//   let dollar_values = fp.map(function (car) {
//     return car.dollar_value;
//   }, cars);
//   return _average(dollar_values);
// };

const getDollarValue = getProp("dollar_value");
const getDollarValues = (data) => fp.map(getDollarValue, data);
let _averageDollarValue = fp.flowRight(_average, getDollarValues);
console.log('练习3: ', _averageDollarValue(cars));


// 练习4: 使用flowRight 写一个sanitizeNames()函数，
// 返回一个下划线连接的小写字符串，爸数组中的name 转换为这种格式：
// 例如：sanitizeNames(["Hello World"]) => ["hello_world"]
let _underscore = fp.replace(/\W+/g, "_"); // 无需改动，并在sanitizeNames中使用它

// const split = (word) => fp.split('_', word);
// const lowerFirst = (list) => fp.map(fp.lowerFirst, list);
// const join = (list) => fp.join('_', list);
// const sanitizeNames = fp.flowRight(join, lowerFirst, split, _underscore);
// console.log('练习4: ', sanitizeNames("Hello World"));

const split = (word) => fp.split(' ', word);
const lowerFirst = (list) => fp.map(fp.lowerFirst, list);
const join = (list) => fp.join(' ', list);
const sanitizeNames = fp.flowRight(_underscore, join, lowerFirst, split);
console.log('练习4: ', sanitizeNames("Hello World"));
